In 1960, chemist Morton Beroza of the U.S. Department of Agriculture suggested using sex pheromones
to jam the insect long-distance mating communication system. He reasoned that if an agricultural area is blanketed with many sources emitting the sex pheromones of a pest species, some or even most males of the species would follow the false trails. Instead of being happily united with appropriate females and producing a new generation of insects, the males would die as confused bachelors.
In 1967, entomologist Harry Shorey at the University of California, Riverside, followed Beroza’s lead and was the first to show that pheromones could be used to disrupt the mating of an insect—in this case cabbage looper moths in the field. Precisely how the pheromones do this job is not known. Researchers speculate that the high loads of pheromone not only confuse male insects, but also camouflage a female’s pheromone emission and cause some males to tune out all sources of the pheromone.
Mating disruption has been a boon for farmers whose crops were plagued by insects that had become immune to broad-spectrum insecticides. In Mexico—where nearly half the tomatoes consumed in the United States are grown—the pinworm once regularly destroyed more than three-quarters of a year’s crop. Then growers began broadcasting the pinworm’s sex pheromone throughout tomato fields by means of plastic tubes attached to stakes or tomato stems or foliage.
Results were dramatic. According to one study only about 4 percent of the females were able to mate under these conditions. In neighboring untreated fields, by contrast, 50 percent of the female pinworms mated. Moreover, only about 30 percent of a year’s growth of tomatoes was lost to pinworm damage in crops treated with mating disruption and other integrated pest management (IPM) measures, such as the use of an insecticide produced by bacteria. Neighboring fields treated with conventional insecticides lost as much as 80 percent of the tomato crop. The IPM approach was also less costly than the conventional approach. With such convincing findings, most growers of tomatoes in Mexico have adopted IPM programs using mating disruption for pinworm control.
Mating disruption has been beneficial for other crops as well. A pilot program to control the codling moth in apple and pear orchards in Oregon, Washington, and California reduced pesticide use by 80 percent and caused damage by this insect to be lower than in conventionally treated orchards. The pilot program’s success boosted the use of codling moth mating disruption in Washington apple orchards from 1,000 acres in 1991 to more than 100,000 acres in 2000—about half the apple acreage in the state. Farmers are also using mating disruption extensively to control cotton pests in Egypt and the United States, rice pests in Spain, peach and nectarine pests in Australia and North America, and grape pests in Europe.
